Telephony.



S. -G. BROWN. y

TELEPHONY. APPLlcATloN FILED Dsc. 16, 1912.

` 1,185,472. Patented May 30,1916.

3 SHEETS-SHEET l.

S.` G.4 BROWN.

TELEPHONY. aPPLlcATloN FILED lDsc. 1s. 1912.

lli/565565, l 55h/h..

S. G. BROWN.

TELEPHONY.

APPLICATION FILED DEC. I6. I9I2.

l ,l 85,472, Patented May 30, 1916.

3 SHEETS-SHEET 3. A I

SIDNEY GEORGE BROWN, OF LONDON, ENGLAND.

TELEPHONY.

Specification of Letters Patent.

Patented May so, 191e.

Application filed December 16, 1912. Serial No. 737,082.

Tonllwwm traag/concern.'

Be it known that I, SIDNEY GEORGE BnowN, a subject of the King of Great Britain, residing at 4 Great ivlnchester street, in the city and county of London, England, have invented certain new and useful Improvements in and Belatingto Telephony, of which the following is a specification.

This invention relates to telephony. In contrast with telegraphy it is of course well understood that the full possibility of dupleX working in telephony is of no value since the operator at the end ot' any line'has no intention of speaking and listening at one and the same time. In telephony, therefore, only simplex working is required but it is obviously desirable to be able to converse in either direction over long distances, and the chief object of the present invention is to provide, in what may be termed simplex telephony, a reliable and sensitive relay system capable of' operating automatically and at any required point in the line so that the distance over which speech is clearly conveyed may be 'considerably increased without involving great expense or necessitating frequent adjustments for the various different conditions that may arise.

Since a telephone station may of course be considered asa transmitting or as a receiving station according as the operator is speaking or listening, I shall refer, for convenience of description. to the two stations between which it is desired to estabi lish communication through a relay system as stations A and B.

According to the present invention each off the two stations A and B has its own relay in the line and means are provided whereby the speaking currents from either one of the two stations not only cause the local circuit of the relay corresponding to that station to become effective in magnify-V ing the speaking currents but also cause the other station to become dlsconnected from its own relay and capable of .receiving thel aforesaid magnified currents. Each relay, which may be of any known kind Suitable for magnifying telephone currents, is conveniently connected across the line and return wires of its respective station through a switch arm movable between back and front stops, the switch arm being normally held against the back stop, in which Electrical connections between the twol relays are so arranged that when the switch arm belonging to one relay is moved so as to make contact with itsfront stop, the connection of this relay with its own station is broken, and in addition the completion is made of a circuit that enables the magnified currents derived from the other 'relay to reach the said station.

The movement of the switch arm of either relay into contact with its front stop is effected by an electrical device or devices, preferably deriving currerl-t from the other relay, as hereinafter described.

In order that the said Iinvention may be clearly understood and readily carried into effect the same will now be described more fully with reference to the accompanying drawlngs 1n which 'Figure 1 represents Ydiagrammatically two l telephone relays with their electricalconnections and cooperating devices for carrying out the invention. Fig. 2 represents a modification of' the system shown in Fig. 1. Fig. 3 is an end elevation and Fig. 4e a side elevation of one ofthe electrical devices hert inbef'ore referred to as being used in el'l'ecting the actuation of the switch arm. Fig. 5 is a diagram of a modification of part of the system shown in Fig. l, and Fig. 5 is a.

detail of construction hereinafter described. Fig. 6 represents diagrannnatically a further modified system' in which the two relays are situated at some distance apart in the line of communication between the two stations. Fig. 7 represents tliagrammatically a modification of the system shown in Fig. l, and Fig. 8 represents a modification ot' the system shown in Fig. 7.

Referring first to Fig. l, A is the relay corresponding to station A and connected therewith by the wires a a', and B is the relay corresponding to station B and connected therewith by the wires t. The connection of the wire a to the relay A is b v way of the condenser A2, and of the wire a. by way of" the switch arm ,-U: similarly the connection of' the wire 7) to ther-clay l is b v way of the condenser B2. and of' the wire b byV way of the switch ai lli. y are the front and back sto] rcspect'iii'cly of the switch arm A3, and /ill the front and back stops of the switch arxnBi.v The locall circuit of the relay Aj includesa local battery AA1, anindi'cator A, and thelpriinaryof an autotransformer A6; similarly the local circuit of the relay `Bv y includes a local battery B4, an indicator B5, and the primary of an auto-transformer B6. The secondary terminals of theauto-transformer A. are connected by way of the leads /caa `to the wire b andthe front stop yesp'ec tively; similarly the secondary terminalsl of the auto-transformer B are connected by wav of the leads b2 b3 to the, Wire 'ai and the front stop a" respectively. `Inthe local4 circuit of the relay A there is connected, in

parallel -witl1.the-priinary of the -autof transformer A6, the Winding of` an lelectromagnct A? in serles with a condenser As; the electromagnet A7 has for lts' armature 'a r'csilicnt reed A9 on which rests one end ofa balanced arm A11. The reed A9 and balanced arni A1" form part of a' circuit including a battery A11 and the winding of an electromagnet A1`; they may also be shunted by a condenser as sliownby A13. The el'ectromagnet A12 'is so"` related to the switch arm B that tlie'flatter serves; as armature to it. The lel'ect'roinagnets A1 and A12 constitute the electrica-l devices hereinbefore referred to as 'serving to control the movements of the switch arm. The connections of the parts B1, B8,- B,B1, B11, B11 and B13' will be understood froni'ithe foregoing description and need not be ldescribed in detail. So long as the reedA is stationary the steady ciu-rent from thelbattery A11 energizes the electromagnet A1'.f"with the result that the latter maintains the switch arm B3 in contact with its back stop 121; similarly with regard, to the reed B1. I These reeds A0 B9 are stationary so long as neither 'of the operators at the two stations A and B is speaking;

its front vstop b1 and thereby completes the circuit of the station B With the secondary terminals ofthe transformer A, the primary of which transformer has 0f course been traversed by the local currents of the relay A simultaneously with the passage of vthese currents through the Winding of the electromagnet A1. When the operator at station Afcea'ses speaking, the steady current from-the battery A11 through the Winding vof the electromagnet A12 is restored and the` switch arm B3 therefore becomes at- `tracted back to its position Ote-contact with back stop b". It' the operator at station B now speaksa precisely similar sequence of events takes place. yIt is importantv to observe that the circuit of one station is automatically prepared for the reception of currents from the relayof the other 'station by the currentsderived from the relay of the latter station.

The means shown in Figui, for actuating lthe switch arm A, Bare to be considered more with reference to their principle of 4action than to their constrilctiong'for instance, it is necessary that the contact of the' switch arms with their front stops should take place sharplyY but without chattering, and for this purpose the actual contact surface ofthev switch arm may be constituted by the free cud of a blade spring attached to the said arm.

In the modification shown in Fig. 2, the

reeds AJ B1 and the balanced arms A1", B10, normally serve to shunt the wmdings of the electromagnets A11 B11 relatively to the bat As regards the electrmnagnetlc vibration l devices' A?, A9. A1 and B1B. B1". it may bc observed that Ithe electrolnagnct winding of either or both of thcln might bc on the l1ne" side ofthe correslmmling relay instead of in the relay local circuit, but the method of connection already described is preferable since the currents available are the magnified currents of the relay. In a modified arrangement the vibration devices might be dispensed with inFig. Alfand the respective relay local circuits themselves include, in series with them,'the windingson the electromagnets, provided the relay local current were in each case strong and steady enough during the periods of inaction of the relays. The arrangements described with reference to Figs. 1 and 2 arehowever preferable. v

One constructional form of the vibration devices is shown in detail in Figs. 3 and -lr and will now be described. The core of the electromagaiet A7 comprises the magnetized steel base A1XX carrying at its poles the upwardly inclined pole pieces proper the ends of whichconverge under the free end of the resilient reed A. The reed is of spring steelhaving a cut-away portion to impart resiliency and is held down by screws upon a knife edge A11. The free end of the reed'carries a' small disk or plate of carbon and the riding end A15 of the balanced arm A is preferably gold, although other material, for instance, osmiumiridi-um alloy, may be used. The balanced arm A10 is carried by a rod or plate A10 l supported horizontally by wires or fibers A11. One wire or fiber passes'v over a pulley and is attached toa spring A10 and the other is secured to the point of an adjusting screw A10 by means of which the torsion of the wires or fibers and hence the sensitiveness of contact of the arm A10 with the carbon on the reed A0 can be accurately adjusted. It is desirable, for the eiicient action of the switch arms that control the relay circuits, that these arms should vmove away from their back stops suddenly and return gradually and it will be understood that a vibration device having a'balanced contact and other parts constructed and arranged as above 'described will bring about the result, since the balanced contact will very quickly respond to vibrations and will be somewhat sluggish in coming to rest. This sudden movement of the switch arms in one direction and their more gradual movement in the opposite direction may however be obtained in other ways.

The electromagnetic vibration devices above describedl operate by practically destroying the electric circuit normally maintained through the reeds and balanced arms. The actual breaking of such a circuit is not however imperative and in some cases may be detrimental since a sustained noise or musical note in the line may cause the vibration device to operate. A form of the device which is not subject to this defect is represented in Fig. 5. The electromagnet AI acts upon the reed A0 as in the `prior construction, but this reed carries a contact -piece forming part of a microphone A20 through which the circuit of the battery ,A11 is completed; the battery circuit also includes the coil A12X which is suspended .in

a strongmagnetic Held and carries then switch arm B1, thus serving the purpose of the electromagnet`A12 in Fig. 1. A comparatively strong battery current normally traverses the microphone A20 and the coil A111. and the latter is adjusted so that under normal conditions the switch arm B3 presses against its back stop. Then however the reed A0 is rapidly vibrated in response to speaking currents, the average strength of the current traversing the microphone, and hence also the coil, is considerably reduced;

' .this is a wellknown effect in telephone microphones and is here utilized to reduce the rent in the coil A12x so much that the coil moves and carries the tonguev B3 into contact with its front stop. The advantage of lthis microphonic form of electromagnetic vibration device is that a sustained note or similar disturbance in the line merely produces a change in the strength of, the current normally traversing the microphone and therefore merely alters the value from which the current strength falls when the reed vibrates. The switch arms carried by the suspended coils may advantageously be carried after the manner of what are sometimes called jockey tongues, that is to say each tongue, say the tongue B3 for example, is rotatably mounted uponthe coil A12X by a pin A111X between the head of which and the boss of the tongue is situated a spring A15X as vseen clearly in Fig, 5% The spring A15X causes suficient friction between the underside of the boss on the tongue B3 and top of the coil to make the coil and tongue move together about their common axis of oscillation so long as no obstruction is offered to the tongue. When however the tongue is obstructed in its movement, the coil can continue to move .in the same angular direction but immediately the coil commences to move in the opposite direction the tongue moves with it.

Hitherto it has been assumed that the two relays and their cooperating devices are situated at one `relay station situated somewhere between the two terminal stations A-and B, and it is natural to suppose that this relay statio'n would be situated about midway between them. Under such circumstances, any noises or disturbances between one terminal station and its relay would be superimposed upon the speaking currents and be magnified proportionately by the relay before being sent on to the distant station. If, however, the two relays were separated, each being placed comparatively near its own station, the noises or other disturbances magnified by it, and superimposed upon the speaking currents, would be only those arising from the reduced length' of line between the said station and its relay. In other words the noises or disturbances arising in the por'- tion of the line between the two separated relays would not be magnified by either of themthat is to say, so far as the relays are concerned thisintermed'iate part of, the line would be illuminated. A relay system adapted to wor-k in this manner is shown in Fig. 6. The dotted' horizontal lines represent the intermediate portion of line between the relays. The electrical connections will be readily understood by inspection of the drawing and are for the most part similar' to those of Fig.'2. It is howeverwto be observed that there is a direct connection, by way'of condensers, from the wlre a, of station A to the wire b of station B; also a direct connection, by way of condensers and the switch arms A3 B1, from nected to the line, and the other end to the back-stop of a switch arm, as it` was 1n the arrangement shown 1n Fig. 2; thls back-stop connection, however, is prefer- 4bration device B".

ably effected through a second switch arm A3X or B3X, respectively, as shown. ln parallel with. the primary of the auto-transformer A3, .which forms part of the local circuit of the relay A", is a circuit containing the condenser A3 and the energizing winding of a vibration device A, the local circuit of this vibrationr device normally serves as a short circuit to the local battery A11, as in the arrangement shown in Fig. Q. The poles of the battery A11 are also connected to electromagnets (L13, @13X of which the electromagnet L13 is adapted for cooperation with the switch arm A3, and the electromagnet @13X adapted for coperation with the,- switch arm A3X. The other ends of these windings or coils are connected across the line as shown. Similar remarks apply to the `switch arms B3 B32 the electromagnets 513, 513x, the battery B11, and the vi- Tfhe batteries A11. B11 are, however, opposed as regards the directio-n of the current supplied by them to the line, and-theelectromagncts (L13, am, and'b13, 6131, are polarized, the result being that the energizing of (L13. m13* bv current from the battery A11 does not move the switch arms A3, A3", nor the energizing of 513, 513x, by current from the battery B11 move the switch arms B3, B3X. Current from the battery A11, however, in energizing Z213, 7213* by way of the intermediate por? tion of the line between the two relays, causes the switch arms B3, B3X, to be actuated; and current from the battery B11, in energizing (1,13, 61,13*, causes the switch arms A3, A3 to be actuated.

The operation is as follows: 1When the operator at station A speaks into his transmitter, the relay A 'is actuated and the local current from the battery A1 actuates the vibration device Ah; the short circuit which this vibration device normally offers to thel battery A11, is, therefore, destroyed, and the current from the battery now traverses the windings of the electromagnets @13E 513x, 7213, and (L13, but owing to the particular manner in which these electromagnets are polarized. only 7213, 6111*. are edective in moving the corresponding switch arms B3, B3". By the moving over of theseY switch arms. the line 7) is placed in circuit with the secondary of the auto-transformer A". and the auto-transformer B is prevented from acting as a short circuit to the currents from the said auto-transformer A3. The latter transformer therefore passes on the magnified currents from the relay A to the distant station B. lt is, of course, understood that simultaneously with the actuation of the vibration device A by current from the local circuit of the relay A', the primary of the auto-trans former A11 is energized, and hence also the secondary of this transformer. When the Operator at station A ceases speaking the parts return to their normal positions. Vhen the operator at B speaks a sequence of operations similar to those already described will take place, as will be understood. The secondary ofthe auto-transformer BG will be placed in circuit with the wires a o of station A, since the switch arms A3, A3X, will be actuated, b-ut not the switch arms B3, B3X.

The type ofV relay employed as the relay A or B may be any convenient forml of magnifying relay suitable for telephonie work, such as the relay described in the specification vof my prior United States Patent No. 1,018,113 of December 24, 1912, or one similar yto the relay therein described but having a granular carbon cell to perform its microphonic functions.

, 1t has already7 been stated that the vibration devices, instead of being worked by current derived from the local circuit of their respective relays, might be worked by the line currents. Since the line currents are, of course, available at any point in the line, a natural development of this modification is the placing of the vibration device at some distance from its corresponding relay; it might for instance be placed close to the transmitting station, and in fact be connected across the transmitter itself. One arrangement of this kind -is shown in Fig. 7,

and will now be described. 'The energizing circuit of the vibration device -A7X together with a condenser A8 are connected directly across the transmitter or across the line near the transn'iitting station and the derived circuit of the device includes the battery u magnet A12 so that the latter causes `the switch arm B3 to disconnect the relay B from the line and place the distant station B inv circuit with the secondary'of theautotransformer A3. Similarly when speaking currents from station B traverse the vibration device B73, the electromagnet D ceases to attract the switch arm D and a steady current from the battery D is sent along the line to the electromagnet B12, and the switch arm A3 is attracted over against its front stop a0 thus disconnecting the relay A from the line and connecting the distant station A with the secondary of the auto-transformer B6.

i In the system above described with reference to Fig. 7, and also in that about to be described with reference to Fig. 8, the line and return wires are normally dead, since the constant presence of a steady current in them would keep the switch arm electromagnets constantly energized. The principle underlying the 'system shown in Fig. 7 and distinguishing it from the system shown in Fig. 1 may advantageously be modiiied as shown in Fig. 8 which will be understood for the most part merely by inspection.` The right and left hand ends of this ligure represent devices and connections operating similarly to those shown in Fig. 7, but itis important to notice that the batteries C and D must be oppositely connected across the transmitters or across the line near the same.

so that if one battery may be said to send a plus current along the line the other sends a minus current. vThe electromagnets-A12 and B12 at the relay station ai'e polarized. the result being that the current from either battery, C or D, traverses the windings of both electromagnets but only one of the latter is operative in attracting its switch arm. For example current from the'battery C causes the electromagnet A12 to attract the switch arm B3 against its front stop b1 but leaves the electromagnet B12 inoperative in its effect upon the switch arm A3. The set of apparatus and connections illustrated in the niid-part of Fig. 8 might be employed several times at intervals between the end stations, and it will be understood that a single vibration device at each station would be effective `in operating all the intermediate relay stations in the same manner as it operates the single relay station shown in the figure.

. I n orderthat the operator atone station may speak to the operator at a distant station, he must first draw the distant operators attention by sending a current which will bringabout. the ringing of a bell or the lighting of a small lamp, as is customary in ordinary telephony. To enable a signaling current to be 'sent from one station to another in my simplex relay system, I may connect up the two stations through inductances as shown for example by E E in Fig. 2, or F F iii Fig. 8. A steady current could then be sent from one station to the other; this current would not affect the relays owing to the presence of the condensers; also the connection between the two 'stations would have no effect during the will be understood that varying currents such as those produced by speaking are pi'evented from traversing the circuits of the batteries C and D owing to inductances in -series in thesel circuits, and that they are prevented from traversing the \\'indings of the electroinagnets A12 and B12 owing to the inherent high self-inductance of these electroinagnet windings.

lVhat I claim and desire to secure by Letters Patent of the United States is l. In a telephonie relay system connecting two stations, a relay electrically connected with the one station, a relay electrically connected with the other station, a switch acting in conjunction with each relay to close the circuit'between the relay a'nd its own station, and electrical means set in action by relay-magnifying speaking currents whereby the actuation of the relay pertaining to one station simultaneously causes the switch in the circuit of the relay of the other station to automatically break the connection between that station and its relay, and establish a. path for'transmission of the aforesaid magnified currents to said station.

2. In a telephone system connecting two stations, relay appa atus comprising for each station a relay electrically connected to the station, a switch normally closing the electrical connection, an electrical device operable by magnified speaking currents derived from the relay, electromagnetic means adapted to operate the other station-to-relay connecting switch under the control of the said electrical device, and means whereby movement of the latter switch from its normal position enables the aforesaid magnied currents to be transmitted to the station corresponding to said switch.

3. In a telephone system connecting two stations, relay apparatus comprising for each station a relay electrically connected to the station, a switch arm forming part of the electrical connection, front and back stops coperating with said switch arm, the back stop being connected to the line side of the aforesaid relay and the front stop to the local side of the relay of the other station,

-nieans keeping the switch aiin normally in to the station, a switch arm vforfning part of the electrical connection, front and back stops coperating with said switch arm, the back lstop being connected to the line side of the relay and the front stop to the local side of the relay of the other station, an

electromagnetic vibratory device operable by the magnified speaking currents derived from the relay, an electromagnetic device for controlling the switch arm of the other relay, and a battery and electrical connections between the two 1electromagnetic devices.

5. In a telephone system connecting two stations, relay apparatus comprising for each station a relay electrically connected to the station, a switch arm formingpart of' the electrical connection, front and back stops cooperating with said switch arm, the back stop heilig connected to the line side of the relay and the front stop to the local side of the relay of the other station, an electroi'nagnetic vibratory device, a transformer electrically connecting the local circuit of the relay with the said vibratory device, an electromagnetic device 'for controlling the switch arm of the other relay, and a battery y and electrical connections between the two electromagnetic devices.

(3. In a telephone system ot' the kind hereinbet'ore described, the combination with a relay electrically connected to each station, a switch arm forming part of lsuch connection, and front and back stops for coperation with said switch arm, of an electromagnet cooperating with said switch arm, a battery in the electromagnet circuit, and means depending for operation upon the magnified speaking currents derived from the other relay for destroying the steady current of the battery.

7. A telephone system consisting in the combination with the telephonie transmitting and receiving apparatus at each terminal station, of a magnifying relay in electrical connection with one. station, a magnifying relay in electrical connection with the other station, electrical means whereby the tion.

magnified speaking currents resulting from the actuation of either relay cause the station of the other relay to be automatically disconnected from its own relay and capable of' receiving the magnified currents from the first relay, and inductances forming a through connection between the stations for ringing-up purposes.

S. In a telephone system connecting'two stations, relay apparatus in respect of each station, comprising a relay electrically connected to the station, a switch arm and a back stop forming part ot' the electrical connection, a front stop electrically connected with the relay of the other station, a vibration device electrically operated by the relay lo al current; a polarized electromagnetic device cooperating with the switch arm, a local battery having the circuit completed through the vibration device and the electromagnetic device, and electrical connections between the polarized electromagnetic devices of the two stations, the polarization being such that the local battery current of either station 'renders operative only the electromagnetic device of the other sta- 9. In a telephone sys-tem connecting two stations, relay apparatus comprising for each station a relay electrically connected to the station, a switch arm forming part of the electrical connection, front and back stops coperating with said switch arm, the back stop being connected to the line iside of the relay and the front stop to the local side of the relay of the other station, a microphonic device operable by the magnied speaking currents derived from the relay, an electromagnetic device for controlling the switch arm of the other relay, and a battery and electrical connections between the two devices.

In testimony whereof I affix my signature in presence of two witnesses.

SIDNEY GEORGE BROWN.

Witnesses: y

T. SELBY VVARDLE,

IALTER J. SKERTEN. 

